1. RADIO AND TELEVISION BROADCASTING
AM Radio
FM Radio
Television

2. 3.4.1 AM Radio Broadcasting 535-1605 kHz 10 kHz carrier spacing
bandwidth of m(t) is 5kHz.
Superheterodyne receiver with intermediate frequency
two frequency components and are produced after the mixer

3. Rejection of the radio signal at the image frequency
Assume there are two received signals
The mixer output consists of the two signals
The RF amplifier bandwidth is designed to be sufficiently narrow so that the image frequency signal is rejected
The IF amplifier has bandwidth of 10kHz to reject signal from adjacent channels.
Desired signal
Interference from image channel

4. 3.4.2 FM Radio Broadcasting
FM Radio Broadcasting
for transmission of voice and music signals (bandwidth of m(t) is 15 kHz)
MHz
200 kHz carrier spacing
peak-frequency deviation 75 kHz
Superheterodyne receiver with intermediate frequency

6. FM-Stereo Broadcasting
Many FM-stereo stations transmit music programs in stereo by using the outputs of two microphones.
A pilot tone at the frequency of 19 kHz is added to the signal for the purpose of demodulating the DSB-SC AM signal.
A monophonic FM receiver can recover the summed signal L+R by using a conventional FM demodulator. Hence, the FM-stereo broadcasting is compatible with the conventional FM.

7. FM Stereo Transmitter

8. FM Stereo Receiver

9. 3.4.3 Television Broadcasting
Commercial TV broadcasting began as black-and-white picture transmission by BBC in 1936.
The two dimensional image is converted to a one-dimensional electrical signal by sequentially scanning the image.
The scanning of the electron beam in the CRT is controlled by two voltage applied across the horizontal and vertical deflection plates.
In commercial TV broadcasting, the bandwidth of the video signal is is limited to W = 4.2 Mhz.
VSB modulation is employed, the total transmission bandwidth is around 6 Mhz.

11. Interlaced pattern with rate 1/60 sec

12. A typical video signal

14. The audio portion of the TV signal is transmitted is limited to W= 10 kHz.
The peak frequency deviation in the FM-modulated signal is selected as 25 kHz, and the FM-signal needs bandwidth of 70 kHz.

17. 3.5 Mobile Radio Systems
Cellular concept

18. Terminologies
The simultaneous transmission between two parties is called full-duplex operation.
In analog cellular system, the 3 kHz audio signal is transmitted via FM using a channel bandwidth of 30 kHz. This represents a bandwidth expansion of approximately a factor of 10.